1. Field of the Invention
The present invention relates to a whitening cosmetic incorporated with kojic acid. In particular, it relates to a kojic acid-containing whitening cosmetic having not only an improved stability against discoloration but also an enhanced whitening effect.
2. Description of the Prior Art
Kojic acid, i.e., 5-hydroxy-2-hydroxymethl-.gamma.-pyrone, is a compound which can be obtained by the fermentation of fungi of, e.g., Aspergillus genus. It is known that the compound functions as a tyrosinase inhibitor. Whitening cosmetics utilizing the function of the compound are known and disclosed in Japanese Patent Publication No. 18,569/81 and Japanese Patent Application (Laid Open) No. 3,538/78.
Whitening cosmetics, in particular cosmetic creams, containing kojic acid as an active ingredient are prone to a discoloration to yellowish brown when exposed to heat or light, and the density of the cosmetics tends to increase with the passage of time, thus impairing their value as an article to be marketed.